Cavity insulation, EPS and cables

[Iceverge]

€100/m3 2 yes ago for us inc vat. 

[Roger440]

Just to update this, ive concluded there too many issues with filling the cavity, and its only 75mm anyway. 

 

Im going to line the inside with rockwall slabs, prob 150mm and panel over with steel cladding. Accepting that i need to do it myself, its not working out more expewnsive than beads on the face of it.

 

Though i will have to extend the wiring out to the relocated sockets, but thats a minor irritation.

[Sparrowhawk]

On 24/11/2022 at 21:25, Nickfromwales said:

You cannot have EPS in contact with PVC electrical cables.

 

On 26/11/2022 at 20:34, Conor said:

I had this debate with my spark in our build. They were running cables directly against the EPS roof panels and I called him out on it. He was of the view that it was ok, unless they were in a potential over heating situation. I impressed the whole plasticiser migration thing, and he was adamant there was no issue. As it happened, he was going though his NICEIC recertification and his assessor visited the site and was of the same view, not a known issue in their industry. 

 

Also, it seems the brittleing of cables is only an issue if they move around and crack... So for hidden cables not an issue anyway.

 

I contacted an EPS bead manufacturer to see what they would say. I'll paraphrase so as not to out them but their technical team was of the view that:

 

"The plasticiser serves to make the cables flexible, but once they are installed they no longer need to be bent or moved. Even if the plasticiser leaches out and the cable becomes brittle it'll next be moved when being replaced, at which point if the outer insulation crack the it’s of no consequence."

 

It's the opposite of everything I've read online, but it seems to makes sense. But I'd want an independent view before going ahead.

 

What do people think?

 

In my case I've also got other blockers to cavity wall insulation as

• blocking the top of our walls with rockwool looks to be impossible without removing the soffits
• none of our air bricks are sleeved
• the previous owner had an 80A cable installed up one cavity, across the loft (under the insulation 🙄) and down the other cavity to a fuse box in the extension and I'd not want that surrounded by insulation.

[Radian]

7 minutes ago, Sparrowhawk said:

In my case I've also got other blockers to cavity wall insulation as

Does this mean you're going down the EWI route? That would involve a considerable amount of additional expense - making the cost to address the problems with injected CWI look tiny. Insulation installers have lots of tricks to manage the problems you've highlighted except for your cable which really needs to be re-run, even though I'm guessing it's already effectively de-rated (you're not really using 19kW are you?)

 

You probably read my views on EPS and cables, which chime with your findings from the supplier. But while I'd personally be OK with an 80A cable on a 32A MCB in insulation, it seems like it might be relatively easy to deal with this one item. Even if it just meant replacing it with a 16mm² SWA cable in the cavity.

[Nickfromwales]

24 minutes ago, Sparrowhawk said:

 

 

I contacted an EPS bead manufacturer to see what they would say. I'll paraphrase so as not to out them but their technical team was of the view that:

 

"The plasticiser serves to make the cables flexible, but once they are installed they no longer need to be bent or moved. Even if the plasticiser leaches out and the cable becomes brittle it'll next be moved when being replaced, at which point if the outer insulation crack the it’s of no consequence."

 

It's the opposite of everything I've read online, but it seems to makes sense. But I'd want an independent view before going ahead.

 

What do people think?

 

In my case I've also got other blockers to cavity wall insulation as

• blocking the top of our walls with rockwool looks to be impossible without removing the soffits
• none of our air bricks are sleeved
• the previous owner had an 80A cable installed up one cavity, across the loft (under the insulation 🙄) and down the other cavity to a fuse box in the extension and I'd not want that surrounded by insulation.

Google some images online of cables which have started fires and come back to me! None in places where they're 'moving' or 'moved frequently'.........why the hell would they be!?!?

The only cables I've seen affected by this have been stitched into the fabric of a building, ergo NOT subject to mechanical manipulation in any way, shape or form.

EPS manufacturer saving their products ass here IMHO.

 

http://enviro-therm.co.uk/wp-content/uploads/2016/07/Polystyrene-melting-to-cables-e1468939790162.jpg

 

Just a pic off the 'net, but pretty much what I discovered in my place when I boarded out the attic. Some genius had crumpled up polystyrene ceiling tiles and had filled every bloody gap in the 1st floor ceiling void with the damn stuff as insulation, encapsulating all the lighting and power cables. The state of the insulation was shocking ( no pun intended ) with the EPS and PVC seemingly becoming 'one'.

 

This thread is an opportunity to avoid even the possibility of this happening, where is the argument to not follow such advice?

 

Case dismissed, and fill your boots if you know better AFAIC.

[Sparrowhawk]

47 minutes ago, Radian said:

Does this mean you're going down the EWI route?

 

Not this time, it means I've put it off until I can line up all the bits (e.g. builder to sort the vents, and prob advise how to block the top of the cavity or do it for me, unless that's a job for the insulation installer; decide who to believe about cables). The cold spell has made it much more pressing.

 

47 minutes ago, Radian said:

I'm guessing it's already effectively de-rated (you're not really using 19kW are you?)

 

I've just grabbed the manual for the cooker out to check. It's a ceramic hob Rangemaster that should use max 32A but recommends a 45A breaker. So that could be 10kW. This second fuseboard/link would be the one an EV charger goes on in a few years, so that's what - another 7kW? So... maybe?

 

47 minutes ago, Radian said:

You probably read my views on EPS and cables, which chime with your findings from the supplier. But while I'd personally be OK with an 80A cable on a 32A MCB in insulation, it seems like it might be relatively easy to deal with this one item. Even if it just meant replacing it with a 16mm² SWA cable in the cavity.

Replacing with a bigger cable would be the easiest way. I get why the previous owners had it put in this way as they'd just had a new engineered wood floor laid in the room between the fuseboard and the new one and didn't want to take it up, but under the floor would have been more sensible and I'd reroute it this way if I could.

Edited December 18, 2022 by Sparrowhawk

[Nick Laslett]

The iCF blocks from Thermohouse used on my build are made from graphite eps beads. They have bolded in the electrical section of their installation manual the following. 
 

Quote

The use of pvc-pvc cable must be placed into conduit to avoid reaction with EPS. Therefore, ensure that all PVC cables are NOT in contact with the EPS.

This short document https://electriciancourses4u.co.uk/useful-resources/what-effects-different-types-of-thermal-insulation-have-on-electrical-insulation/

 

Puts the onus on the insulation manufacturer, to check their products data sheet. 
 

Found this 2004 ministry of defence document advising against electrical cable with EPS. 
 

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/33549/spec34.pdf

 

I pretty confident that 18th edition electrical regs will be consistent with these requirements. 
 

I believe BASF invented the graphite eps beads. They may have some details on this issue. 

[Sparrowhawk]

2 hours ago, Nickfromwales said:

The only cables I've seen affected by this have been stitched into the fabric of a building, ergo NOT subject to mechanical manipulation in any way, shape or form.

EPS manufacturer saving their products ass here IMHO.

 

That has been my suspicion. If the "good news" comes from those with a vested interest in selling it - I am doubtful. A reason for posting here as a sanity check, as sitting in a 15C I start to soften and think "well maybe they're right and it would be okay"

 

2 hours ago, Nickfromwales said:

 

http://enviro-therm.co.uk/wp-content/uploads/2016/07/Polystyrene-melting-to-cables-e1468939790162.jpg

 

Just a pic off the 'net, but pretty much what I discovered in my place when I boarded out the attic. Some genius had crumpled up polystyrene ceiling tiles and had filled every bloody gap in the 1st floor ceiling void with the damn stuff as insulation, encapsulating all the lighting and power cables. The state of the insulation was shocking ( no pun intended ) with the EPS and PVC seemingly becoming 'one'.

Yes that's horrific. Different to the 'green goo' issue with some cables.

 

Thanks for posting, it's good to hear from someone who has seen the problem first hand.